POS1132 PATTERNS OF JOINT SURGERY IN THE TEN YEARS PRIOR TO PRIMARY KNEE REPLACEMENT IN ENGLAND AND SWEDEN – A POPULATION-BASED CASE-CONTROL STUDY
Authors: A. Dell’isola, T. Appleyard, D. Yu, C. Hellberg, G. Thomas, A. Turkiewicz, G. Peat, M. Englund
Journal: Annals of the Rheumatic Diseases (2022)

Background Primary knee replacement (KR) is an effective intervention for end-stage knee osteoarthritis (OA). However, there are no definitive recommendations for the timing at which patients should receive this surgery, potentially resulting in differences in referral patterns depending on geographical area or the clinicians‘ preferences. Objectives To investigate the prevalence of meniscus, knee ligament and knee synovial surgeries as well as knee osteotomy and hip replacement (HR) across the ten years preceding a KR in cases and controls in England and Sweden. Methods This was a multi-national, population-based, case-control study within England and Sweden. Cases underwent primary TKR and controls, matched using risk-set sampling by age, sex and practice/region, did not. Electronic healthcare databases were used; the Clinical Practice Research Datalink (CPRD) in England, and the Health Register of Skåne (Sweden’s southernmost region) in Sweden. ICD-10 codes and KVÅ codes in Sweden and Medcodes (SNOMED CT (UK edition) and Read codes) in England were used to identify subjects aged ≥45 years who underwent primary KR between 1 st January 2015 and 31 st December 2019. Eligible cases had to be registered for ≥10 years prior to the primary KR (index date), and have no record of prior KR in that period. Office of Population Censuses and Surveys (OPCS) codes in England and ICD-10 codes in Sweden were used to identify selected orthopaedic surgeries. Meniscal (e.g. excision, resection, repair) and ligament surgery (e.g. ligament reconstruction, replacement, suture) were included, as well as osteotomy (e.g. angle, rotational or displacement osteotomy of the knee or lower leg). Hip replacement (HR) (any primary HR) was also included, to evaluate the rate at which patients undergoing KR also undergo further major arthroplasty in the years preceding this – The annual prevalence of having at least one recorded surgery for each type in each of the 10 years preceding KR was estimated using Poisson regression models and expressed per 1,000 people. Results We identified 6,337 and 47,010 subjects who underwent a knee replacement between 2015 and 2019 in southern Sweden and England, respectively (Table 1). Overall, the prevalence of all analysed surgeries was consistently lower in the controls with minimal trends detectable throughout follow-up in both England and Sweden (Figure 1). Table 1. demographic Sweden England Cases (n=6,337) Controls (n=6,337) Cases (n=47,010) Controls (n=47,010) Age, mean (SD ) 69.0 (8.9) 68.9 (9.1) 69.6 (9.6) 69.6 (9.6) Female Sex, n (% ) 3,585 (56.6%) 3,585 (56.6%) 26,154 (55.6%) 26,154 (55.6%) Surgeries, n Hip replacement 562 324 3,933 1,889 Meniscus 384 44 8,659 833 Ligaments 16 5 90 11 Synovial 164 15 369 30 Osteotomy 98 3 107 5 On the other hand, an increasing trend among the cases, signifying a higher prevalence of surgeries when nearing KR, was observed for HR and meniscal surgeries in both nations. The prevalence of HR was similar in England and southern Sweden at all-time points showing an increase most noticeable in the 3 years before KR. The prevalence of meniscus surgery in England was higher than the one observed in Sweden throughout the follow-up. Prevalence in England increased most noticeably in the four years prior to KR reaching 33.2 (95%CI 31.6, 34.9) surgeries per 1,000 people in the year preceding KR. In Sweden, the prevalence of meniscus surgery remained between four and eight surgeries per 1,000 people until the last year prior to KR when the prevalence increased to 13.8 (95%CI 11.9, 16.2) surgeries per 1,000 people. Conclusion HR and meniscal surgeries are common procedures that a person is likely to have experienced in the ten years prior to a KR. Comparing England and southern Sweden, we noticed similar prevalence and trends for what concerns HR suggesting similar practice in the two healthcare systems. Meniscus surgeries were more frequently utilised in England. Nevertheless, in both countries, a marked increase in the prevalence of this surgery was observed in the last years prior to the KR. Disclosure of Interests None declared